DE1170030B - Arc extinguishing chamber for low-voltage circuit breakers - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: H 02 c

German class: 21 c - 35/06

Number: 1 170 030

File number: L 38547 VIII d / 21 c

Filing date: March 24, 1961

Opening day: May 14, 1964

The invention relates to an arc extinguishing chamber with electrically conductive and / or insulating Stacks of extinguishing plates for arc splitting or elongation and for the dionization of cut-off arcs high currents.

The breaking capacity of an arc chamber of this type is now 40 to 50 kA _{e //} for voltages up to 500 volts alternating current. One tries to achieve higher switch-off values by connecting several pole tracks in parallel, whereby the switch-off capability is divided between the individual arcing chambers.

There are also circuit breakers have recently become known that in the event of a short circuit Work current-limiting and interrupt the surge short-circuit current in the first half-wave. For such Switching devices that achieve a breaking capacity of more than 100 kA ^ and their contacts open during the surge short-circuit current rise, forward currents of 80 up to 150 kA occur if the first half-wave is more than double in an asymmetrical short circuit - depending on the switching angle and power factor - has the rms value as the peak value.

It is known that arcs, which are ignited in a chamber that surrounds them on all sides, fill the chamber space in a very short time and in its direction of migration similar to a piston generate strong head wave consisting of compressed air, while behind the arc gases in a vacuum is formed for a short time. This causes a stagnation of the arc gases. At a strong congestion of the gases, the pressure in the upper part of the arc chamber increases so high that the conductive arc gases thrown back into the ignition space around the contacts by the dynamic pressure which leads to reignition of the arc in this room. Particularly disadvantageous affects this phenomenon in arcing chambers for circuit breakers with current limiting Switch-off characteristic because of the absolutely necessary, the quality of the current limitation Strongly influencing, steep arc voltage rise not achieved with accumulating arc gases can be.

It is known to have chimney-like openings in an arc extinguishing chamber for discharging the arc gases to be provided. It is also known to have one associated with the contact side of the contact system To arrange the conclusion of the arc extinguishing chamber, which contains nozzle-like openings.

In the known switches, the arc-extinguishing chamber for
Low voltage circuit breaker

Applicant:

Licentia Patent-Verwaltungs-G. mb H.,
Frankfurt / M., Theodor-Stern-Kai 1

Named as inventor:
Heinz Fehling, Einfeld

arc quenching chamber at the same time the switching chamber, d. H. the space in which the arc occurs.

According to the invention, a significant improvement is achieved in that the control room is an independent, formed from arc-proof material held inside the quenching chamber is whose walls are at such a distance from the arcing chamber walls that between air shafts for the supply of fresh air are available for them and the extinguishing chamber walls.

So one is the switch room (ignition chamber) and

Constructive special chamber taking into account the extinguishing space. The supply of fresh air for the purpose of pressure equalization takes place in the simplest way that the walls of the switch room (the Ignition chamber) have a certain distance from the walls of the extinguishing chamber. So you need no special nozzle-like openings.

According to a further development of the inventive concept, the extinguishing chamber walls can be perforated at the level of the ignition chamber, so that fresh air can also enter the air shafts from here.
The invention will be explained in more detail with reference to the drawing, in which two exemplary embodiments are shown. Show it

F i g. 1 and 2 a transverse and a longitudinal section through an extinguishing chamber according to the invention,

Fig. 3a and 3b arc current and light

arc voltage curves i - f (t) or u - f (t) for an arc chamber of known design,

3c and 3d arc current and arc voltage curves i = f (t) and u = f (t) for an arc extinguishing chamber according to the invention, FIG. 4 shows the cross section through an arc extinguishing chamber with perforated walls.

409 589/385

The in F i g. 1 and 2 shown arc extinguishing chamber consists of the outer chamber 1 with Arc quenchers 2 and insulating partitions 3 and the ignition chamber 4. The fixed contact piece of the associated switch is denoted by 5, the movable one by 6. The contacts are already opened; the development of the arc is indicated by dashed lines, its direction of migration with indicated by dashed arrows. The tear-off contacts 7 and 8, which are kept particularly narrow, are of the walls 9 of the ignition chamber 4 closely surround. The quenching plates 2 are wedge-shaped with the usual Incisions 10 provided and sit with their legs 11 on the ignition chamber 4 like a rider. the Ignition chamber 4 is kept so narrow that between the ignition chamber walls 9 and the side walls 10 of the chamber air shafts 12 are created through which fresh air can flow into the extinguishing chamber (Arrows L), if a negative pressure should arise in the area of the tear-off contacts.

In Fig. 4 is yet another embodiment shown. With it, the side walls of the extinguishing chamber 1 are level with the ignition chamber 4 broken through, so that 13 air can flow through the window. The window openings 13 can be covered by perforated plates 14 like a sieve.

From the oscillograms Fig. 3a to 3d, which represent the arc current i and the arc voltage u as a function of the time i, the significantly improved mode of operation of the quenching chamber according to the invention (Figs. 3 c and 3 d) compared to a previously used chamber (F i g. 3 a and 3 b).

While the oscillogram of the arc voltage of a known arcing chamber (Fig. 3 b) numerous Reignitions and a relatively low arc voltage, which results in a long deletion time and a correspondingly high load on the switch results from the oscillograms F i g. 3 d and 3 c a steep increase in arc voltage can be seen, due to which the Current is switched off in a current-limiting manner in a time of less than a half-wave.

Claims (3)

Patent claims: L. arc chamber for low-voltage circuit breakers, in which a switch room with its walls closely surrounds the contacts, characterized in that the Switch room as an independent, held within the arcing chamber, made of arc-proof material existing chamber is formed, the walls of which at such a distance from the Quenching chamber walls stand that air shafts between them and the quenching chamber walls Supply of fresh air are available. 2. arc extinguishing chamber according to claim 1, characterized in that the arcing chamber walls are perforated at the level of the switching chamber. 3. arc extinguishing chamber according to claim 1 and 2, characterized in that the openings the arcing chamber walls are covered by perforated plates like a sieve. Considered publications:
German Auslegeschrift No. 1 040 647.
053 067, 1 079 717. 1 sheet of drawings 409 589/385 5.64 © Bundesdruckerei Berlin